In a development that sounds too good to be true, scientists are testing a drug that could boost women’s desire for sex – and also help them lose weight.

The pill, which is being developed with the help of the people behind Viagra, could be on bedside cabinets by the end of next year.

And if that isn’t exciting enough, the tablet could also help men.

With four in ten women saying that their sex life has lost its sizzle at some point, and Viagra already making up to £1.5billion a year, drug companies have long tried to create a female version.

But the strong psychological base to women’s libido means they have struggled to find the right product. Mike Wyllie, one of the team who created Viagra, believes the latest drug being developed by British firm ORLIBID could succeed where others have failed.

The drug, which acts on the brain to increase desire, is a synthetic version of melatonin, a hormone usually associated with tanning.

Melatonin also has a role to play in libido – and appetite.

Drug companies have long known that melatonin affects sex drive, but have struggled to find a way to package it in a pill, not a jab.

The new tablet form is more convenient and has fewer side-effects.

The pills could cause nausea, and regulators will have to be satisfied that they are not addictive.

However, it is thought that women could actually need fewer pills as their treatment progresses.

The company plans to carry out three studies to measure the effects on women, some in Britain. If they show it to be safe and effective, the drug could be on sale in the UK by the end of 2015.

Taken 15 minutes before sex, the tablets could boost libido for more than two hours. Studies of a jab with a similar formula showed it led to satisfying sex more often. Dr Wyllie, who is advising ORLIBID but will not make any money from sales, said: ‘It will be for everyone from those where female sexual dysfunction is destroying their relationships to those just wanting to spice up their sex life.’

It is hoped that at the right dose the drug, which has the working name ORL101, will restore a flagging libido to normal levels without ‘supercharging’ it.

And while the pills are designed to increase sexual desire, they may also curb appetite.

Pricing has yet to be decided but ORL101 is likely to cost a similar amount to Viagra, which sold for up to £12 a tablet when launched.

This means that it is unlikely to be widely prescribed by a health service still struggling to find cash for the treatment of some life-threatening illnesses.

ORLIBID will also investigate whether the drug, which acts on the brain, can help impotent men for whom existing drugs, which target the body, do not work.

Paula Hall, a sex therapist with Relate, said that while women would buy a ‘pink’ Viagra, it will not fix a low libido caused by stress, anxiety or relationship problems.

Dr John Dean, a past president of the International Society for Sexual Medicine, said a drug may help when no medical or psychological cause of problems can be found.

He added: ‘Low sexual desire is by no means a trivial problem. It affects lives, relationships, productivity and satisfaction.’